AbstractObjectWriter (Drill : 1.20.3 API)

java.lang.Object
- org.apache.drill.exec.vector.accessor.writer.AbstractObjectWriter

All Implemented Interfaces:

ColumnWriter, ObjectWriter

Direct Known Subclasses:

AbstractArrayWriter.ArrayObjectWriter, AbstractScalarWriterImpl.ScalarObjectWriter, AbstractTupleWriter.TupleObjectWriter, UnionWriterImpl.VariantObjectWriter
```
public abstract class AbstractObjectWriter
extends Object
implements ObjectWriter
```
Abstract base class for the object layer in writers. This class acts as the glue between a column and the data type of that column, per the JSON model which Drill uses. This base class provides stubs for most methods so that type-specific subclasses can simply fill in the bits needed for that particular class.

Constructor Summary

Constructors
Constructor and Description

AbstractObjectWriter()

Constructors
Constructor and Description
`AbstractObjectWriter()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`ArrayWriter`	`array()`
`void`	`copy(ColumnReader from)` Copy a single value from the given reader, which must be of the same type as this writer.
`DictWriter`	`dict()`
`abstract void`	`dump(HierarchicalFormatter format)`
`abstract WriterEvents`	`events()` The internal state behind this writer.
`boolean`	`isProjected()` Whether this writer is projected (is backed by a materialized vector), or is unprojected (is just a dummy writer.) In most cases, clients can ignore whether the column is projected and just write to the writer.
`boolean`	`nullable()` Whether this writer allows nulls.
`ScalarWriter`	`scalar()`
`ColumnMetadata`	`schema()` Returns the schema of the column associated with this writer.
`void`	`setNull()` Set the current value to null.
`void`	`setObject(Object value)` Generic technique to write data as a generic Java object.
`String`	`toString()`
`TupleWriter`	`tuple()`
`ObjectType`	`type()` Return the object (structure) type of this writer.
`VariantWriter`	`variant()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.drill.exec.vector.accessor.ObjectWriter
writer

- Constructor Detail
  - AbstractObjectWriter
```
public AbstractObjectWriter()
```
- Method Detail
  - scalar
```
public ScalarWriter scalar()
```
    Specified by:
    
    scalar in interface ObjectWriter
  - tuple
```
public TupleWriter tuple()
```
    Specified by:
    
    tuple in interface ObjectWriter
  - array
```
public ArrayWriter array()
```
    Specified by:
    
    array in interface ObjectWriter
  - variant
```
public VariantWriter variant()
```
    Specified by:
    
    variant in interface ObjectWriter
  - dict
```
public DictWriter dict()
```
    Specified by:
    
    dict in interface ObjectWriter
  - events
```
public abstract WriterEvents events()
```
    Description copied from interface: ObjectWriter
    
    The internal state behind this writer. To be used only by the implementation, not by the client.
    
    Specified by:
    
    events in interface ObjectWriter
  - schema
```
public ColumnMetadata schema()
```
    Description copied from interface: ColumnWriter
    
    Returns the schema of the column associated with this writer.
    
    Specified by:
    
    schema in interface ColumnWriter
    
    Returns:
    
    schema for this writer's column
  - type
```
public ObjectType type()
```
    Description copied from interface: ColumnWriter
    
    Return the object (structure) type of this writer.
    
    Specified by:
    
    type in interface ColumnWriter
    
    Returns:
    
    type indicating if this is a scalar, tuple or array
  - nullable
```
public boolean nullable()
```
    Description copied from interface: ColumnWriter
    
    Whether this writer allows nulls. This is not as simple as checking for the TypeProtos.DataMode.OPTIONAL type in the schema. List entries are nullable, if they are primitive, but not if they are maps or lists. Unions are nullable, regardless of cardinality.
    
    Specified by:
    
    nullable in interface ColumnWriter
    
    Returns:
    
    true if a call to ColumnWriter.setNull() is supported, false if not
  - setNull
```
public void setNull()
```
    Description copied from interface: ColumnWriter
    
    Set the current value to null. Support depends on the underlying implementation: only nullable types support this operation. throws IllegalStateException if called on a non-nullable value.
    
    Specified by:
    
    setNull in interface ColumnWriter
  - setObject
```
public void setObject(Object value)
```
    Description copied from interface: ColumnWriter
    Generic technique to write data as a generic Java object. The type of the object must match the target writer. Primarily for testing.
    - Scalar: The type of the Java object must match the type of the target vector. String or byte[] can be used for Varchar vectors.
    - Array: Write the array given an array of values. The object must be a Java array. The type of the array must match the type of element in the repeated vector. That is, if the vector is a Repeated Int, provide an int[] array.
    - Tuple (map or row): The Java object must be an array of objects in which the members of the array have a 1:1 correspondence with the members of the tuple in the order defined by the writer metadata. That is, if the map is (Int, Varchar), provide a Object[] array like this: {10, "fred"}.
    - Union: Uses the Java object type to determine the type of the backing vector. Creates a vector of the required type if needed.
    Specified by:
    
    setObject in interface ColumnWriter
    
    Parameters:
    
    value - value to write to the vector. The Java type of the object indicates the Drill storage type
  - isProjected
```
public boolean isProjected()
```
    Description copied from interface: ColumnWriter
    
    Whether this writer is projected (is backed by a materialized vector), or is unprojected (is just a dummy writer.) In most cases, clients can ignore whether the column is projected and just write to the writer. This flag handles those special cases where it is helpful to know if the column is projected or not.
    
    Specified by:
    
    isProjected in interface ColumnWriter
  - copy
```
public void copy(ColumnReader from)
```
    Description copied from interface: ColumnWriter
    
    Copy a single value from the given reader, which must be of the same type as this writer.
    
    Specified by:
    
    copy in interface ColumnWriter
    
    Parameters:
    
    from - reader to provide the data
  - dump
```
public abstract void dump(HierarchicalFormatter format)
```
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class AbstractObjectWriter

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.drill.exec.vector.accessor.ObjectWriter

Constructor Detail

AbstractObjectWriter

Method Detail

scalar

tuple

array

variant

dict

events

schema

type

nullable

setNull

setObject

isProjected

copy

dump

toString